Cheque Receipt Acknowledgement Letter. Door Number and Street's Name, Area Name, City.Make a copy of each letter before sending it. How to fill out the Acceptance of Service Document for Washington State? 1. Enter your full name in the designated field. 2. Keep a copy of all post office receipts. We also encourage you to think about how to say "thank you" in a personal and meaningful way. When should a gift acknowledgment be sent? Whose signature goes in the line name of person acknowledging. The notary or the principal?